Deuteronomy 34:8

34:8 The Israelites mourned for Moses in the deserts of Moab for thirty days; then the days of mourning for Moses ended.

Deuteronomy 2:14

2:14 Now the length of time it took for us to go from Kadesh Barnea to the crossing of Wadi Zered was thirty-eight years, time for all the military men of that generation to die, just as the Lord had vowed to them.